1. Field of the Invention
The invention relates to a transducer mounted on a stringed musical instrument to transduce the vibration of strings to an electric signal, and to a stringed musical instrument including the same, and more particularly, to a transducer and a stringed musical instrument which realize improved sound quality of reproduced sound obtained by output from the transducer.
2. Description of the Related Art
An acoustic guitar which is a plucked string instrument having a hollow body and a plurality of strings is one of conventionally known stringed musical instruments. Sound directly heard when such an acoustic guitar is played includes sound produced by the vibration of air caused by the vibration of the strings, sound produced by the vibration of a top of a body caused by the vibration of strings propagating to the top, and sound produced through a sound hole of the body.
As an acoustic guitar, also utilized is that of a type in which a transducer transducing the vibration of strings into an electric signal is provided in a body, and electric sound can be reproduced through an amplifier and so on.
Here, as an acoustic guitar provided with the aforesaid transducer, known are a conventional structure 1 (see FIG. 11 and U.S. Pat. No. 5,123,325 B), a conventional structure 2, and a conventional structure 3 (see JP H7-5881 A) which are described below.
In the conventional structure 1, as shown in FIG. 11, a transducer 51 made of a piezoelectric device which is a long, narrow piece is disposed under a saddle 52. Concretely, the transducer 51 and the saddle 52 are sequentially put in a saddle slot 53A of a bridge 53 mounted on a top of a not-shown body, so that the transducer 51 is sandwiched by the bridge 53 and the saddle 52.
In the conventional structure 2, a transducer including a piezoelectric device is in a plate form and is mounted on an outer surface of a body with an adhesive or the like.
In the conventional structure 3, a transducer includes a coil positioned inside a sound hole and is capable of transducing the vibration of strings into an electric signal by electromagnetic induction of the coil.
In the above-described conventional structure 1, however, since tension of strings gives a downward force to the saddle 52, a relatively strong compressive force constantly acts on the transducer 51. This obstructs free movement of the transducer 51 itself, so that there is a tendency that the complicated vibration of the top caused by performance cannot be thoroughly transduced. This results in a problem that sound reproduced via an amplifier or the like has sound quality and tone quite different from actual performance sound that is directly heard from an acoustic guitar and reproducibility of the performance sound is thus impaired.
Further, in the conventional structure 2, though the transducer senses the vibration of the body, the sensed vibration greatly varies depending on which position of the body it is mounted. Therefore, the work of adjusting the mounting position of the transducer in order to obtain good sound quality and tone becomes difficult and complicated, and the conventional structure 2 thus has a problem of an increased load required for this work.
On the other hand, in the conventional structure 3, since the vibration of a body is not sensed, produced sound is different in sound quality and tone from performance sound that is heard when the transducer is not used. That is, since performance sound heard when the acoustic guitar is played is sound produced by the vibration mainly of a top of the body, the conventional structure 3 sensing mainly the vibration of strings has a problem of insufficient reproducibility.
Further, as a transducer such as a pickup capable of transducing the vibration of strings into an electric signal in a plucked string instrument such as an acoustic guitar as described above, known is that of a type provided with a plate-formed or a sheet-formed piezoelectric device. This piezoelectric device is mounted on a body of a stringed musical instrument via an adhesive layer made of rubber and is connected to an amplifier or the like via a lead wire. Therefore, the vibration of the strings when the stringed musical instrument is played propagates to the body, the adhesive layer, and the piezoelectric device in this order, and electric sound can be reproduced according to an electric signal outputted by the piezoelectric device.
However, in this structure, though the adhesive layer attenuates the vibration of the strings before it propagates to the piezoelectric device, it is difficult to obtain a sufficient attenuating operation only with the adhesive layer, and when the string is plucked with a force which is not very strong, electric output level of the piezoelectric device sometimes reaches the maximum. Consequently, even plucking with a stronger force does not increase the output level and causes almost no change of the output level, which causes a problem that tone and quality of reproduced sound are not satisfactory enough.
Moreover, there is a tendency that a frequency band in which a good attenuating operation is exhibited becomes relatively narrow, so that it becomes difficult to obtain a sufficient attenuating operation in a frequency band requiring the attenuation. As a result, for example, in a case where the adhesive layer exhibits a less sufficient attenuating operation in a mid/low register than in a high register, the output level unnaturally differs between these registers, which also causes deterioration of sound quality and tone.